Unfit, unsuitable, improper, inappropriate, unfitting, inapt, unhappy, infelicitous are comparable when they mean not right with respect to what is required or expected under the circumstances or demanded by the end, use, or, function in view. (Except for this denial of rightness, the terms otherwise correspond in applications and in implications to the affirmative adjectives as discriminated at FIT ).
See also: Fit vs Suitable vs Meet vs Proper vs Appropriate vs Fitting vs Apt vs Happy vs Felicitous